HDFS-8176. Record from/to snapshots in audit log for snapshot diff report. Contributed by J. Andreina.

(cherry picked from commit cf6c8a1b4ee70dd45c2e42ac61999e61a05db035)

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -151,6 +151,9 @@ Release 2.8.0 - UNRELEASED
 
     HDFS-8052. Move WebHdfsFileSystem into hadoop-hdfs-client. (wheat9)
 
+    HDFS-8176. Record from/to snapshots in audit log for snapshot diff report.
+    (J. Andreina via jing9)
+
   OPTIMIZATIONS
 
     HDFS-8026. Trace FSOutputSummer#writeChecksumChunks rather than

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java

@@ -7400,8 +7400,12 @@ public class FSNamesystem implements Namesystem, FSNamesystemMBean,
     } finally {
       readUnlock();
     }
-
-    logAuditEvent(diffs != null, "computeSnapshotDiff", null, null, null);
+    String fromSnapshotRoot = (fromSnapshot == null || fromSnapshot.isEmpty()) ?
+        path : Snapshot.getSnapshotPath(path, fromSnapshot);
+    String toSnapshotRoot = (toSnapshot == null || toSnapshot.isEmpty()) ?
+        path : Snapshot.getSnapshotPath(path, toSnapshot);
+    logAuditEvent(diffs != null, "computeSnapshotDiff", fromSnapshotRoot,
+        toSnapshotRoot, null);
     return diffs;
   }